surfaceCreated：显示java.lang.NullPointerException [英] surfaceCreated : java.lang.NullPointerException
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问题描述
我试图让定制的相机应用程序，但每当我运行我的程序，
获得 -
的不幸的是应用程序已经停止的
LogCat中：
05-30 14：47：09.844：D / CameraCaptureActivity（797）：getCameraInstance（）照相机：空
05-30 14：47：09.855：D / CameraCaptureActivity（797）：getCameraInstance（）开放：空
05-30 14：47：09.855：D / CameraCaptureActivity（797）：mCamera ::空
05-30 14：47：09.895：D / CameraCaptureActivity（797）：mCamera ::空
05-30 14：47：09.895：D / CameraCaptureActivity（797）：mSurfaceHolder :: android.view.SurfaceView$4@40d06ef8
05-30 14：47：09.924：D / CameraCaptureActivity（797）：mCamera preVIEW :: com.example.demo.Camera $ P $ {PVIEW 40d06860 V.E ..... ......我。 0,0-0,0}
05-30 14：47：09.924：D / CameraCaptureActivity（797）的FrameLayout :: android.widget.FrameLayout {40cfa7d8 V.E ..... ......我。 0,0-0,0＃7f080000应用：ID / camera_ preVIEW}
05-30 14：47：09.954：D / CameraCaptureActivity（797）：captureButton :: android.widget.Button {40cfad50 VFED..C。 ......一世。 0,0-0,0＃7f080001应用：ID / button_capture}
05-30 14：47：04.327：D / AndroidRuntime（797）：关闭VM
05-30 14：47：04.327：W / dalvikvm（797）：主题ID = 1：螺纹未捕获的异常退出（组= 0x40a71930）
05-30 14：47：04.458：E / AndroidRuntime（797）：致命异常：主要
05-30 14：47：04.458：E / AndroidRuntime（797）：显示java.lang.NullPointerException
05-30 14：47：04.458：E / AndroidRuntime（797）：在com.example.demo.Camera preview.surfaceCreated（相机preview.java：33）
05-30 14：47：04.458：E / AndroidRuntime（797）：在android.view.SurfaceView.updateWindow（SurfaceView.java:569）
05-30 14：47：04.458：E / AndroidRuntime（797）：在android.view.SurfaceView.access $ 000（SurfaceView.java:86）
05-30 14：47：04.458：E / AndroidRuntime（797）：在android.view.SurfaceView $ 3.on preDraw（SurfaceView.java:174）
05-30 14：47：04.458：E / AndroidRuntime（797）：在android.view.ViewTreeObserver.dispatchOn preDraw（ViewTreeObserver.java:680）
05-30 14：47：04.458：E / AndroidRuntime（797）：在android.view.ViewRootImpl.performTraversals（ViewRootImpl.java:1842）
05-30 14：47：04.458：E / AndroidRuntime（797）：在android.view.ViewRootImpl.doTraversal（ViewRootImpl.java:989）
05-30 14：47：04.458：E / AndroidRuntime（797）：在android.view.ViewRootImpl $ TraversalRunnable.run（ViewRootImpl.java:4351）
05-30 14：47：04.458：E / AndroidRuntime（797）：在android.view.Choreographer $ CallbackRecord.run（Choreographer.java:749）
05-30 14：47：04.458：E / AndroidRuntime（797）：在android.view.Choreographer.doCallbacks（Choreographer.java:562）
05-30 14：47：04.458：E / AndroidRuntime（797）：在android.view.Choreographer.doFrame（Choreographer.java:532）
05-30 14：47：04.458：E / AndroidRuntime（797）：在android.view.Choreographer $ FrameDisplayEventReceiver.run（Choreographer.java:735）
05-30 14：47：04.458：E / AndroidRuntime（797）：在android.os.Handler.handleCallback（Handler.java:725）
05-30 14：47：04.458：E / AndroidRuntime（797）：在android.os.Handler.dispatchMessage（Handler.java:92）
05-30 14：47：04.458：E / AndroidRuntime（797）：在android.os.Looper.loop（Looper.java:137）
05-30 14：47：04.458：E / AndroidRuntime（797）：在android.app.ActivityThread.main（ActivityThread.java:5041）
05-30 14：47：04.458：E / AndroidRuntime（797）：在java.lang.reflect.Method.invokeNative（本机方法）
05-30 14：47：04.458：E / AndroidRuntime（797）：在java.lang.reflect.Method.invoke（Method.java:511）
05-30 14：47：04.458：E / AndroidRuntime（797）：在com.android.internal.os.ZygoteInit $ MethodAndArgsCaller.run（ZygoteInit.java:793）
05-30 14：47：04.458：E / AndroidRuntime（797）：在com.android.internal.os.ZygoteInit.main（ZygoteInit.java:560）
05-30 14：47：04.458：E / AndroidRuntime（797）：在dalvik.system.NativeStart.main（本机方法）
错误：
显示java.lang.NullPointerException
订单：
mCamera.set previewDisplay（surfaceHolder）;
摄像头preview.java：
公共类相机preVIEW延伸SurfaceView工具
SurfaceHolder.Callback {公共静态最后弦乐LOG_TAG =镜头preVIEW
私人SurfaceHolder mSurfaceHolder;
私人相机mCamera;//该构造背景下获取和摄像头
@燮pressWarnings（德precation）
公共摄像头preVIEW（上下文的背景下，相机摄像头）{
超级（上下文）;
this.mCamera =摄像头;
Log.d（CameraCaptureActivity.LOG_TAGmCamera ::+ mCamera）;
this.mSurfaceHolder = this.getHolder（）;
this.mSurfaceHolder.addCallback（本）;
this.mSurfaceHolder.setType（SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS）;
Log.d（CameraCaptureActivity.LOG_TAGmSurfaceHolder ::+ mSurfaceHolder）;
}@覆盖
公共无效surfaceCreated（SurfaceHolder surfaceHolder）{
尝试{
mCamera.set previewDisplay（surfaceHolder）;
Log.d（CameraCaptureActivity.LOG_TAG，surfaceCreated（套preVIEW）::+ mCamera）;
mCamera.start preVIEW（）;
Log.d（CameraCaptureActivity.LOG_TAG，surfaceCreated（启动preVIEW）::+ mCamera）;
}赶上（IOException异常五）{
//为空白，现在
}
}@覆盖
公共无效surfaceDestroyed（SurfaceHolder surfaceHolder）{
mCamera.stop preVIEW（）;
Log.d（CameraCaptureActivity.LOG_TAG，surfaceDestroyed（停止preVIEW）::+ mCamera）;
mCamera.release（）;
}@覆盖
公共无效surfaceChanged（SurfaceHolder surfaceHolder，INT格式，
INT宽度，高度INT）{
//启动preVIEW新设置
尝试{
mCamera.set previewDisplay（surfaceHolder）;
mCamera.start preVIEW（）;
}赶上（例外五）{
//故意留空为测试
}
}
}CameraCaptureActivity.java：
公共静态最后弦乐LOG_TAG =CameraCaptureActivity;私人相机mCamera;私人相机preVIEW mCamera preVIEW;/ **当第一次创建活动调用。 * /
@覆盖
公共无效的onCreate（捆绑savedInstanceState）{
super.onCreate（savedInstanceState）;
的setContentView（R.layout.main）;
mCamera = getCameraInstance（）;
Log.d（CameraCaptureActivity.LOG_TAGmCamera ::+ mCamera）;
mCamera preVIEW =新相机preVIEW（这一点，mCamera）;
Log.d（CameraCaptureActivity.LOG_TAGmCamera preVIEW ::+ mCamera preVIEW）;
的FrameLayout preVIEW =（的FrameLayout）findViewById（R.id.camera_ preVIEW）;
preview.addView（mCamera preVIEW）;
Log.d（CameraCaptureActivity.LOG_TAG的FrameLayout ::+ preVIEW）; 按钮captureButton =（按钮）findViewById（R.id.button_capture）;
Log.d（CameraCaptureActivity.LOG_TAGcaptureButton ::+ captureButton）;
captureButton.setOnClickListener（新View.OnClickListener（）{
@覆盖
公共无效的onClick（视图v）{
mCamera.takePicture（NULL，NULL，mPicture）;
Log.d（CameraCaptureActivity.LOG_TAGmCamera.takePicture ::+ mCamera）;
}
}）;
}/ **
如果它不能得到* Helper方法访问摄像机返回null
*相机或不存在
*
* @返回
* /
私人相机getCameraInstance（）{
摄像头摄像头= NULL;
Log.d（CameraCaptureActivity.LOG_TAGgetCameraInstance（）照相机：+摄像头）;
尝试{
相机= Camera.open（）;
Log.d（CameraCaptureActivity.LOG_TAGgetCameraInstance（）开放：+摄像头）;
}赶上（例外五）{
//不能得到相机或不存在
}
返回摄像头;
}PictureCallback mPicture =新PictureCallback（）{
@覆盖
公共无效onPictureTaken（字节[]数据，相机摄像头）{
文件PictureFile的= getOutputMediaFile（）;
如果（PictureFile的== NULL）{
返回;
}
尝试{
FOS的FileOutputStream =新的FileOutputStream（PictureFile的）;
fos.write（数据）;
fos.close（）;
}赶上（FileNotFoundException异常五）{ }赶上（IOException异常五）{
}
}
};私有静态文件getOutputMediaFile（）{
文件mediaStorageDir =新的文件（
环境
.getExternalStoragePublicDirectory（Environment.DIRECTORY_PICTURES）
MyCameraApp）;
如果（！mediaStorageDir.exists（））{
如果（！mediaStorageDir.mkdirs（））{
Log.d（MyCameraApp，无法创建目录）;
返回null;
}
}
//创建一个媒体文件名
字符串的timeStamp =新的SimpleDateFormat（YYYYMMDD_HHMMSS）
.format（新的Date（））;
文件媒体文件;
媒体文件=新的文件（mediaStorageDir.getPath（）+文件分割符
+IMG_+ +的timeStamp.JPG）; 返回媒体文件;
}
}
解决方案在这里，您
mCamera终止返回null。这是由于摄像头的初始化不当。
使用Camera.open（）;进行初始化。也为您在初始化过程引发的任何异常。另外，还要确保您拥有所有必需的权限清单文件＆LT;使用许可权的android：NAME =android.permission.CAMERA/＆GT;
＆LT;使用特征的android：NAME =android.hardware.camera.autofocus/＆GT;＆LT;使用特征的android：NAME =android.hardware.camera/＆GT;
尝试{
相机= Camera.open（）;
Log.d（CameraCaptureActivity.LOG_TAGgetCameraInstance（）开放：+摄像头）;
}赶上（例外五）{
//检查这里的任何异常
}I am trying to make Custom Camera app, but whenever i run my program,
getting -
Unfortunately App has Stopped
LogCat:
05-30 14:47:09.844: D/CameraCaptureActivity(797): getCameraInstance()Camera:: null 05-30 14:47:09.855: D/CameraCaptureActivity(797): getCameraInstance()open:: null 05-30 14:47:09.855: D/CameraCaptureActivity(797): mCamera:: null 05-30 14:47:09.895: D/CameraCaptureActivity(797): mCamera :: null 05-30 14:47:09.895: D/CameraCaptureActivity(797): mSurfaceHolder :: android.view.SurfaceView$4@40d06ef8 05-30 14:47:09.924: D/CameraCaptureActivity(797): mCameraPreview :: com.example.demo.CameraPreview{40d06860 V.E..... ......I. 0,0-0,0} 05-30 14:47:09.924: D/CameraCaptureActivity(797): FrameLayout :: android.widget.FrameLayout{40cfa7d8 V.E..... ......I. 0,0-0,0 #7f080000 app:id/camera_preview} 05-30 14:47:09.954: D/CameraCaptureActivity(797): captureButton :: android.widget.Button{40cfad50 VFED..C. ......I. 0,0-0,0 #7f080001 app:id/button_capture} 05-30 14:47:04.327: D/AndroidRuntime(797): Shutting down VM 05-30 14:47:04.327: W/dalvikvm(797): threadid=1: thread exiting with uncaught exception (group=0x40a71930) 05-30 14:47:04.458: E/AndroidRuntime(797): FATAL EXCEPTION: main 05-30 14:47:04.458: E/AndroidRuntime(797): java.lang.NullPointerException 05-30 14:47:04.458: E/AndroidRuntime(797): at com.example.demo.CameraPreview.surfaceCreated(CameraPreview.java:33) 05-30 14:47:04.458: E/AndroidRuntime(797): at android.view.SurfaceView.updateWindow(SurfaceView.java:569) 05-30 14:47:04.458: E/AndroidRuntime(797): at android.view.SurfaceView.access$000(SurfaceView.java:86) 05-30 14:47:04.458: E/AndroidRuntime(797): at android.view.SurfaceView$3.onPreDraw(SurfaceView.java:174) 05-30 14:47:04.458: E/AndroidRuntime(797): at android.view.ViewTreeObserver.dispatchOnPreDraw(ViewTreeObserver.java:680) 05-30 14:47:04.458: E/AndroidRuntime(797): at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1842) 05-30 14:47:04.458: E/AndroidRuntime(797): at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:989) 05-30 14:47:04.458: E/AndroidRuntime(797): at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:4351) 05-30 14:47:04.458: E/AndroidRuntime(797): at android.view.Choreographer$CallbackRecord.run(Choreographer.java:749) 05-30 14:47:04.458: E/AndroidRuntime(797): at android.view.Choreographer.doCallbacks(Choreographer.java:562) 05-30 14:47:04.458: E/AndroidRuntime(797): at android.view.Choreographer.doFrame(Choreographer.java:532) 05-30 14:47:04.458: E/AndroidRuntime(797): at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:735) 05-30 14:47:04.458: E/AndroidRuntime(797): at android.os.Handler.handleCallback(Handler.java:725) 05-30 14:47:04.458: E/AndroidRuntime(797): at android.os.Handler.dispatchMessage(Handler.java:92) 05-30 14:47:04.458: E/AndroidRuntime(797): at android.os.Looper.loop(Looper.java:137) 05-30 14:47:04.458: E/AndroidRuntime(797): at android.app.ActivityThread.main(ActivityThread.java:5041) 05-30 14:47:04.458: E/AndroidRuntime(797): at java.lang.reflect.Method.invokeNative(Native Method) 05-30 14:47:04.458: E/AndroidRuntime(797): at java.lang.reflect.Method.invoke(Method.java:511) 05-30 14:47:04.458: E/AndroidRuntime(797): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793) 05-30 14:47:04.458: E/AndroidRuntime(797): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560) 05-30 14:47:04.458: E/AndroidRuntime(797): at dalvik.system.NativeStart.main(Native Method)Error:
java.lang.NullPointerException
Line:
mCamera.setPreviewDisplay(surfaceHolder);
CameraPreview.java:
public class CameraPreview extends SurfaceView implements SurfaceHolder.Callback { public static final String LOG_TAG = "CameraPreview"; private SurfaceHolder mSurfaceHolder; private Camera mCamera; // Constructor that obtains context and camera @SuppressWarnings("deprecation") public CameraPreview(Context context, Camera camera) { super(context); this.mCamera = camera; Log.d(CameraCaptureActivity.LOG_TAG, "mCamera :: " +mCamera); this.mSurfaceHolder = this.getHolder(); this.mSurfaceHolder.addCallback(this); this.mSurfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS); Log.d(CameraCaptureActivity.LOG_TAG, "mSurfaceHolder :: " +mSurfaceHolder); } @Override public void surfaceCreated(SurfaceHolder surfaceHolder) { try { mCamera.setPreviewDisplay(surfaceHolder); Log.d(CameraCaptureActivity.LOG_TAG, "surfaceCreated (setPreview) :: " +mCamera); mCamera.startPreview(); Log.d(CameraCaptureActivity.LOG_TAG, "surfaceCreated (startPreview) :: " +mCamera); } catch (IOException e) { // left blank for now } } @Override public void surfaceDestroyed(SurfaceHolder surfaceHolder) { mCamera.stopPreview(); Log.d(CameraCaptureActivity.LOG_TAG, "surfaceDestroyed (stopPreview) :: " +mCamera); mCamera.release(); } @Override public void surfaceChanged(SurfaceHolder surfaceHolder, int format, int width, int height) { // start preview with new settings try { mCamera.setPreviewDisplay(surfaceHolder); mCamera.startPreview(); } catch (Exception e) { // intentionally left blank for a test } } }CameraCaptureActivity.java:
public static final String LOG_TAG = "CameraCaptureActivity"; private Camera mCamera; private CameraPreview mCameraPreview; /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); mCamera = getCameraInstance(); Log.d(CameraCaptureActivity.LOG_TAG, "mCamera:: " + mCamera); mCameraPreview = new CameraPreview(this, mCamera); Log.d(CameraCaptureActivity.LOG_TAG, "mCameraPreview :: " + mCameraPreview); FrameLayout preview = (FrameLayout) findViewById(R.id.camera_preview); preview.addView(mCameraPreview); Log.d(CameraCaptureActivity.LOG_TAG, "FrameLayout :: " + preview); Button captureButton = (Button) findViewById(R.id.button_capture); Log.d(CameraCaptureActivity.LOG_TAG, "captureButton :: " + captureButton); captureButton.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { mCamera.takePicture(null, null, mPicture); Log.d(CameraCaptureActivity.LOG_TAG, "mCamera.takePicture :: " + mCamera); } }); } /** * Helper method to access the camera returns null if it cannot get the * camera or does not exist * * @return */ private Camera getCameraInstance() { Camera camera = null; Log.d(CameraCaptureActivity.LOG_TAG, "getCameraInstance()Camera:: " + camera); try { camera = Camera.open(); Log.d(CameraCaptureActivity.LOG_TAG, "getCameraInstance()open:: " + camera); } catch (Exception e) { // cannot get camera or does not exist } return camera; } PictureCallback mPicture = new PictureCallback() { @Override public void onPictureTaken(byte[] data, Camera camera) { File pictureFile = getOutputMediaFile(); if (pictureFile == null) { return; } try { FileOutputStream fos = new FileOutputStream(pictureFile); fos.write(data); fos.close(); } catch (FileNotFoundException e) { } catch (IOException e) { } } }; private static File getOutputMediaFile() { File mediaStorageDir = new File( Environment .getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES), "MyCameraApp"); if (!mediaStorageDir.exists()) { if (!mediaStorageDir.mkdirs()) { Log.d("MyCameraApp", "failed to create directory"); return null; } } // Create a media file name String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss") .format(new Date()); File mediaFile; mediaFile = new File(mediaStorageDir.getPath() + File.separator + "IMG_" + timeStamp + ".jpg"); return mediaFile; } }
解决方案Here you
mCamerais returning null. This is due to improper initialization of camera. UseCamera.open();to initialize it. Also check for any exceptions thrown in process of initialization. Also make sure that you have all necessary permissions in manifest file<uses-permission android:name="android.permission.CAMERA" /> <uses-feature android:name="android.hardware.camera.autofocus" /> <uses-feature android:name="android.hardware.camera" /> try { camera = Camera.open(); Log.d(CameraCaptureActivity.LOG_TAG, "getCameraInstance()open:: " + camera); } catch (Exception e) { // Check here for any exceptions }
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